InAlN/GaN/Si heterostructures and field-effect transistors with lattice matched and tensely or compressively strained InAlN

Properties of InAlN/GaN heterostructures and field-effect transistors with nearly lattice matched (InN=18%) and tensely (13%) or compressively (21%) strained InAlN barrier layer were evaluated. The sheet charge density increased from 1.1×1013 to 2.2×1013 cm−2 with decreased InN mole fraction. The saturation drain current as well as the peak extrinsic transconductance increased inversely proportional to the InN mole fraction—from 1 A/mm to 1.4 A/mm (VG=2 V) and from 190 to 230 mS/mm. On the other hand, the threshold voltage shifted to higher values with increased InN mole fraction. The pulsed current-voltage measurements (1 μs pulse width) yielded relatively low and nearly identical gate lag for all devices investigated. These results show that InAlN/GaN heterostructures with tensely strained InAlN can be useful for high-frequency and high-power devices and with compressively strained InAlN might be useful for the preparation of enhancement mode GaN-based devices.